searching ex on Facebook

I am so sad. My ex husband was a cheater so I know I'm sensitive but I remarried a wonderful man. Today I seen he searched is ex fiancé on Facebook. I feel so sad. I know he was just curious but I can't help feeling insecure especially since I had his baby seven weeks ago and have some self esteem problems since. He is mad at me because I've been quiet today but I just can't help it. I spoke to him and he said he was just curious be aide a friend brought up her name.